Car running lean, any suggestions?

MATTKNIGHT · 06-06-2003, 01:43 PM

Okay, guys, I will start by saying sorry if this is long winded. I want to give an accurante account as to whats going on. I have a 95 gt, 72000 miles. I installed long tubes, off road h pipe, flows, cold air, msd 6al, new distributer (oem replace), msd coil and i think thats ablout it. I ecountered a problem a few months ago when my car started running lean. I checked my fuel press- 36psi @ idle. I replaced my o2 sensors hoping it would help, to no avail. I replaced my fuel filter and got nothing. I cannot figure out what the prob is. I checked every chilton/haynes type manual for help and got nothing. I am kicking a soft fail check eng light. It comes on during heavy accel. Downloaded the fault and got "left bank running lean" and "right bank running lean" as well as an "egr" code. The only modification that was not a direct bolt on was the headers. Everyone knows how they interfere with the smog lines in the pass side eng bay. I reset the comp numerous time as well as checked and reset the timing at least 7 times. Please help me, my car lost so much power in the 3800 - 4500. There is a signifigant loss in power throughout my rpm range as well. My great running car is giving me a headache. I got beat by a Honda the other week. I need help...

Stang_Crazy · 06-07-2003, 04:02 PM

Was the 36 psi at idle with the vacuum line DISCONNECTED?

If you have an adjustable fuel pressure regulator, try bumping the FP up to 39-40 psi at idle with the vacuum line disconnected.

drtbiker · 06-08-2003, 06:38 PM

maybe a weak fuel pump if not make sure u adjust the fp with the vac line off. Did u look at ur plugs?? How do they look.

later

Coupe50h · 06-09-2003, 01:13 AM

My plugs indicated my car being lean, finally the car started stalling recently, today i pulled the fuel filter (Which wasnt very old) and it was so clogged! i replaced it today and it idles real good, and no stalling so far, i realize you replaced yours, but never can do it enough, my tank is obviously full of crud, plus i always run the tank low.

hope you fix it.

MATTKNIGHT · 06-09-2003, 08:22 AM

Hey, just to give you guys more info...
My spark plugs are definitely white, running lean w/o doubt. My fuel pressure as stated above was with vacuum connected. Replaced my fuel filter AGAIN and still haveing problems. Ford tells me they wont work on it because I have modified the car. Dont understand what they're deal is. I just want this damn thing fixed. Any more ideas from you guys would be greatly appreciated. Thanks.
Matt--

Stang_Crazy · 06-09-2003, 05:43 PM

Disconnect the vaccum line and set your fuel pressure to 38-40 psi. That should solve the problem...take the car out and run it for a while. When you get back home, check your plugs. If they're white, try bumping the fp up a few more psi.

SilverSN95 · 06-09-2003, 09:27 PM

I can only add my 2 cents from past experience with my old 86 GT. I had a lean running condition with it once that turned out to be a leaking EGR valve. If I remember correctly (this was about 10 years ago), the car just didn't want to run smooth. I ran the codes and the 'running lean" codes came up. As a trick I remember spraying the egr (diaphram) with water and the idle smoothed right out. Replaced the EGR and all was good.

Hope this helps

MATTKNIGHT · 06-11-2003, 08:11 AM

Alright, just to make sure it wasnt my fuel press I checked it w/ vaccuum discon. I read 39 psi at idle. Seems to me this should be good. I am getting fed up with the car so last night I started working on it. I took the top end of the motor off, including the heads. I saw no problems, even replaced all the gaskets to be sure no probs would occur. There is a crossover tub on the back of the heads, I plugged the heads instead of reinstalling the tube. During reassembly I decided to ditch all the emissions **** on the pass side of the eng. (down by the headers) I left the smog pump on and didnt plug it. The EGR is just flowing free. I plugged the vaccuum lines running to all the valves associated with the emissions stuff. After finishing everything I take the car for a drive. It fell flat on its face, stumbling like a maniac anywhere above 2800 RPM at wot. I am pissed. I cant get this thing to run right. PLEASE any more advice?? I am on the verge of selling this POS and buying an 03 Cobra.

strokedandchoked · 02-13-2009, 07:04 PM

ok, i have a 95 gt, 437 stroker, msd ignition, bbk CAI, the whole nine yards. I ran into the same issue you are and I went through all the ins and outs of changing my plugs, fuel pump, filter, lines, injectors, everything! Then i finally took it to a shop and had them run a comptression test and found out that i was running 15.1.... with that they re-mapped the ecu which was already chipped and programmed. if you have chipped it, the 94 and 95 5.0's tend to become retarted, in a timing sense once you think you have completed tuning. Reseting your computer doesnt keep the ecu from acting up once its already being dumb. Try finding a professional tuning shop, preferably a race performance/ racing shop and have them re-write your fuel curve. IF your car still runs lean, replace the ecu with non OEM one and see what that does. Everyone who owns or has owned a 94 or 95 has run into this same problem time and time again. Good luck and let me know how it turns out.

USMC302 · 02-25-2009, 10:48 AM

This is a pretty old post, glad you worked your issue out though.

lees gt · 03-08-2009, 03:52 PM

Matt,what was the problem in the end? I'm running a bone stock 94gt in the UK with the same problem..i've tried everything except the ECU.
Regards Lee

06-06-2003, 01:43 PM	#1
MATTKNIGHT Registered Member Join Date: Jun 2003 Location: MOUNTAINHOME, IDAHO Posts: 20	Car running lean, any suggestions? Okay, guys, I will start by saying sorry if this is long winded. I want to give an accurante account as to whats going on. I have a 95 gt, 72000 miles. I installed long tubes, off road h pipe, flows, cold air, msd 6al, new distributer (oem replace), msd coil and i think thats ablout it. I ecountered a problem a few months ago when my car started running lean. I checked my fuel press- 36psi @ idle. I replaced my o2 sensors hoping it would help, to no avail. I replaced my fuel filter and got nothing. I cannot figure out what the prob is. I checked every chilton/haynes type manual for help and got nothing. I am kicking a soft fail check eng light. It comes on during heavy accel. Downloaded the fault and got "left bank running lean" and "right bank running lean" as well as an "egr" code. The only modification that was not a direct bolt on was the headers. Everyone knows how they interfere with the smog lines in the pass side eng bay. I reset the comp numerous time as well as checked and reset the timing at least 7 times. Please help me, my car lost so much power in the 3800 - 4500. There is a signifigant loss in power throughout my rpm range as well. My great running car is giving me a headache. I got beat by a Honda the other week. I need help... __________________ MATT KNIGHT 1995 5.0, msd 6al, msd coil, bbk longtubes, bbk offroad, 2 chamber flows, power tower shift, 98 gt wheels

06-07-2003, 04:02 PM	#2
Stang_Crazy It's never clean enough! Join Date: Jan 1999 Location: Shaler, PA Posts: 1,542	Was the 36 psi at idle with the vacuum line DISCONNECTED? If you have an adjustable fuel pressure regulator, try bumping the FP up to 39-40 psi at idle with the vacuum line disconnected. __________________ ~Dan 2001 SVT Lightning 89' GT : Taking up garage space and waiting for a buyer... Rice Hater's Club - Member #11

06-08-2003, 06:38 PM	#3
drtbiker Registered Member Join Date: Jan 2002 Location: Mt. Prospect,IL Posts: 474	maybe a weak fuel pump if not make sure u adjust the fp with the vac line off. Did u look at ur plugs?? How do they look. later __________________ 87-ford-mustang-SOLD! mods: 3:73's, off road h-pipe, b303 cam in gt- 40 motor w/ Power Plus intake, edelbrock 70mm tb & egr spacer, 72mm C&L, bbk long tubes, tremec tranny, centerforce dual friction clutch, upr and lwr CA's 255lph FP and soon more to come.... when i have money again SOME ADVICE Don't do burn outs in reverse it is very expensive New times with dead hook on dr's 13.27@103 with 2.0 60 foots w/100lb system Fastest time to date: 12.8@113

06-09-2003, 01:13 AM	#4
Coupe50h Registered Member Join Date: Aug 2002 Location: SanAntonio, Tx Posts: 957	My plugs indicated my car being lean, finally the car started stalling recently, today i pulled the fuel filter (Which wasnt very old) and it was so clogged! i replaced it today and it idles real good, and no stalling so far, i realize you replaced yours, but never can do it enough, my tank is obviously full of crud, plus i always run the tank low. hope you fix it. __________________ X-Texas highway patrol ssp 1990 coupe - exploder Gt-40 iron heads, Explorer intake, 19 lber's. E-cam. crane 1.7 rollers. 190fp. 75mm maf. 65mm tb, tubular subframe connectors, mac cai, Asp crank pulley, T-5, king cobra clutch, flowtech 1-5/8 unequals, mac X-pipe Frpp driveshaft, lakewood Lca's. race weight 3,160 12.69 @ 107.35, 1.71 60' 26x8.5 drag's 3.90 gear 13.20 @ 106.91 - 235/60/15 firestones 2.3 60' 3.27 gear

06-09-2003, 08:22 AM	#5
MATTKNIGHT Registered Member Join Date: Jun 2003 Location: MOUNTAINHOME, IDAHO Posts: 20	More info Hey, just to give you guys more info... My spark plugs are definitely white, running lean w/o doubt. My fuel pressure as stated above was with vacuum connected. Replaced my fuel filter AGAIN and still haveing problems. Ford tells me they wont work on it because I have modified the car. Dont understand what they're deal is. I just want this damn thing fixed. Any more ideas from you guys would be greatly appreciated. Thanks. Matt-- __________________ MATT KNIGHT 1995 5.0, msd 6al, msd coil, bbk longtubes, bbk offroad, 2 chamber flows, power tower shift, 98 gt wheels

06-09-2003, 05:43 PM	#6
Stang_Crazy It's never clean enough! Join Date: Jan 1999 Location: Shaler, PA Posts: 1,542	Disconnect the vaccum line and set your fuel pressure to 38-40 psi. That should solve the problem...take the car out and run it for a while. When you get back home, check your plugs. If they're white, try bumping the fp up a few more psi. __________________ ~Dan 2001 SVT Lightning 89' GT : Taking up garage space and waiting for a buyer... Rice Hater's Club - Member #11

06-09-2003, 09:27 PM	#7
SilverSN95 Registered Member Join Date: May 2002 Location: Ontario Posts: 39	I can only add my 2 cents from past experience with my old 86 GT. I had a lean running condition with it once that turned out to be a leaking EGR valve. If I remember correctly (this was about 10 years ago), the car just didn't want to run smooth. I ran the codes and the 'running lean" codes came up. As a trick I remember spraying the egr (diaphram) with water and the idle smoothed right out. Replaced the EGR and all was good. Hope this helps __________________ Al, 94 Mustang GT 3.55 gears Magnapack mufflers with 2.5" tails STEEDA TRI-AX Shifter MAC pulleys

06-11-2003, 08:11 AM	#8
MATTKNIGHT Registered Member Join Date: Jun 2003 Location: MOUNTAINHOME, IDAHO Posts: 20	More info yet.... Alright, just to make sure it wasnt my fuel press I checked it w/ vaccuum discon. I read 39 psi at idle. Seems to me this should be good. I am getting fed up with the car so last night I started working on it. I took the top end of the motor off, including the heads. I saw no problems, even replaced all the gaskets to be sure no probs would occur. There is a crossover tub on the back of the heads, I plugged the heads instead of reinstalling the tube. During reassembly I decided to ditch all the emissions **** on the pass side of the eng. (down by the headers) I left the smog pump on and didnt plug it. The EGR is just flowing free. I plugged the vaccuum lines running to all the valves associated with the emissions stuff. After finishing everything I take the car for a drive. It fell flat on its face, stumbling like a maniac anywhere above 2800 RPM at wot. I am pissed. I cant get this thing to run right. PLEASE any more advice?? I am on the verge of selling this POS and buying an 03 Cobra. __________________ MATT KNIGHT 1995 5.0, msd 6al, msd coil, bbk longtubes, bbk offroad, 2 chamber flows, power tower shift, 98 gt wheels

02-13-2009, 07:04 PM	#9
strokedandchoked Registered Member Join Date: Feb 2009 Posts: 1	Re: Car running lean, any suggestions? ok, i have a 95 gt, 437 stroker, msd ignition, bbk CAI, the whole nine yards. I ran into the same issue you are and I went through all the ins and outs of changing my plugs, fuel pump, filter, lines, injectors, everything! Then i finally took it to a shop and had them run a comptression test and found out that i was running 15.1.... with that they re-mapped the ecu which was already chipped and programmed. if you have chipped it, the 94 and 95 5.0's tend to become retarted, in a timing sense once you think you have completed tuning. Reseting your computer doesnt keep the ecu from acting up once its already being dumb. Try finding a professional tuning shop, preferably a race performance/ racing shop and have them re-write your fuel curve. IF your car still runs lean, replace the ecu with non OEM one and see what that does. Everyone who owns or has owned a 94 or 95 has run into this same problem time and time again. Good luck and let me know how it turns out.

02-25-2009, 10:48 AM	#10
USMC302 Registered Member Join Date: Apr 2001 Location: Gallatin, Tn Posts: 1,326	Re: Car running lean, any suggestions? This is a pretty old post, glad you worked your issue out though. __________________

03-08-2009, 03:52 PM	#11
lees gt Registered Member Join Date: Mar 2009 Posts: 1	Re: Car running lean, any suggestions? Matt,what was the problem in the end? I'm running a bone stock 94gt in the UK with the same problem..i've tried everything except the ECU. Regards Lee

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